Fix challenge validation panic when follow-up hits ALLOW (#1278)

* fix(localization): correct formatting of Swedish loading message

* fix(main): correct formatting and improve readability in main.go

* fix(challenge): add difficulty and policy rule hash to challenge metadata

* docs(challenge): fix panic when validating challenges in privacy-mode browsers

lib/localization/localization_test.go

@@ -31,7 +31,7 @@ func TestLocalizationService(t *testing.T) {
 		"vi":    "Đang nạp...",
 		"zh-CN": "加载中...",
 		"zh-TW": "載入中...",
-		"sv" : "Laddar...",
+		"sv":    "Laddar...",
 	}
 
 	var keys []string